Few political observers saw Trump winning the presidential election. Afterward, some election forecasters ate crow. One actually ate a bug. But despite the inevitable lamentations — and recriminations — about election forecasts, there has been little rigorous evaluation of their performance. So we did one.

As of Nov. 3, those who thought Brexit was at least somewhat likely — only 215 of the 1,740 — give Trump a 30 percent chance of winning. Those who thought Brexit was at least somewhat unlikely give him only a 15 percent chance.

Early on, forecasters thought the race was a toss-up. But over time, McCrory’s chances have dropped to 30 percent. Even though McCrory trails Cooper by about 1 point in the poll averages, forecasters are not optimistic about his chances on Election Day.

About three months ago, the forecast for Trump was remarkable: There was a decent chance that Trump would spend less, in inflation-adjusted dollars, than did John McCain in 2008. McCain, let’s recall, accepted public funding for the general election and therefore had his fundraising and spending limited (unlike his opponent, Barack Obama, who did not accept public funding).

Every day seems to bring another story about nervous Republican House and Senate candidates, wondering if Donald Trump is going to cost them their seats. Here’s the interesting thing: Yes, the odds are against the Republicans’ retaining control of the Senate, though they will likely continue to control the House. But it’s still not clear that Trump is (yet) hurting Republicans running for Congress.

Trump is deeply unpopular with the electorate and this is making Senate Republicans nervous.
But three months of predictions from the forecasters at Good Judgment don’t suggest any clear impact of Trump’s likely nomination on the Republicans’ chances of retaining their Senate majority.

Every election year brings out a fresh crop of Bold Predictions of Imminent Third-Party Success. The political scientist Brendan Nyhan has compiled years of these predictions. They mainly conform to the usual tropes of punditry: a vague sense that “something is in the air,” enough weasel words to maintain plausible deniability when — surprise! — No Labels, Americans Elect, or Mark Zuckerberg doesn’t end up in the White House.

Today’s primary elections will tell us a lot more about whether Donald Trump is likely to win a majority of delegates to the Republican convention. In particular, the Florida and Ohio contests are key. Both states are “winner-take-all” and could therefore supply a treasure trove of delegates.

Which Republican will have the most delegates after the Super Tuesday contests, and which will actually win the nomination? If there’s a difference in how people answer these questions, then it tells us the chance that Donald Trump might lose the nomination.

We’ve partnered with Good Judgment to do crowd-sourced forecasts for 2016. Good Judgment has had success aggregating the predictions of individual forecasts (sometimes beating prediction markets). As of this writing, about 1,300 people have made predictions for the Iowa caucus.